In numerous locations of the human anatomy, a primary conduit is connected with one or more secondary conduits that branch off from the primary conduit. In some cases the secondary branches conduct fluid into the primary conduit, while in other cases the secondary branches conduct fluid away from the primary conduit.
The human vasculature includes many examples of primary conduits that have secondary branches. One example of a primary conduit is the aorta. In the aortic arch region, three arteries branch off from the aorta. Those three arteries are the brachiocephalic artery, the left common carotid artery, and the left subclavian artery, and they conduct fluid away from the aorta.
The ductal system of the pancreas provides another example of a primary conduit with secondary branches. The main pancreatic duct receives enzymes that flow into the duct from the side branches.
The left and right intrahepatic ducts of the liver provide yet another example of primary conduits with secondary branches. The intrahepatic ducts receive bile that flows into the common hepatic duct
Conduits within the human body can experience a variety of problems. For example, conduits can have strictures that cause the conduit to become occluded. In some cases, plaque or embolic material can create an occlusion. In the pancreas and liver, for example, stones and other conditions can occlude the pancreatic, bile, and hepatic ducts.
An aneurysm, another potential problematic condition associated with body conduits, is a weakening of the wall of a conduit that causes a bulge in the wall as a result of pressure within the conduit. The bulged wall may burst if the pressure is not relieved. For example, arteries such as the aortic arch can experience aneurysms.
Implantable stent graft devices can be used to treat various problems afflicting conduits. In general, a stent graft is a tubular device which is composed of a membrane supported by a frame. For example, stent grafts can be installed in the location of a stricture to create an open passageway for fluid flow. Stent grafts can also treat aneurysms by providing a conduit liner to relieve the pressure on the weakened wall of an aneurysm.
When stent grafts are installed in conduits that have branches, the membranous wall covering of the stent graft has the potential to block the fluid flow between the conduit and the branches. Therefore, provisions that allow fluid flow between a conduit containing a stent graft and the conduit's branches are desirable. For example, in some cases, stent grafts can include discrete flow path sites in the membranous wall covering of the stent graft (e.g., fenestrations, tubes, channels, etc.). The discrete flow paths are intended to be located in areas on the wall of the stent graft that are in alignment with the anastomoses of the branches. However, such alignment can be challenging to achieve on a consistent basis.
The anatomical configuration of conduit networks, such as the vasculature or the pancreatic, hepatic, and biliary ductal systems, can be unique in every person. That is, the branches from the primary conduits, or the bifurcation of two primary conduits, are likely to be in different locations, and be different sizes, from one person to the next.